Tunnelized scanners or processors, including X-ray or risk contraband scanners, are used for detecting contraband at schools, warehouses, correctional facilities, mail screening, courthouse security, airports, and commercial inspection applications. These scanners employ a tunnel housing, typically shielded and often wired in part about the tunnel isolation devices (curtains), a conveying device, a bed assembly housing in which the conveying device is located, and outer skins. The tunnel housing typically has a top portion and side portions, which together with a top surface of the conveyor bed assembly housing, form a substantially enclosed area. The tunnel housing is also formed with entrance and exit openings that are covered by isolation device curtains. The conveyor devices are typically conveyor belts, and may be rollers or other conveyor means. An example of prior art scanners is provided in U.S. Pat. No. 6,304,629 entitled Compact Scanner Apparatus And Method.
An isolation device substantially covers each of the tunnel entrance and exit openings and is typically in the form of slit curtains containing lead held in a vinyl or fabric sheet. One slit leaded fabric curtain is attached to a flat bracket or framing at the entrance opening, and the other slit leaded fabric curtain is attached at the exit opening. Isolation devices permit the passage of conveyed objects into the substantially enclosed area formed by the tunnel housing and the top portion of the bed assembly housing. The fabric curtains are typically X-ray scatter lead shielded, and may also substantially shield light, noise, heat, cold, moisture, welding sparks, electrostatic or electromagnetic fields, dust, gasses or chemical vapors while the conveyed objects are being analyzed, imaged, processed or treated.
A disadvantage to the prior art is that the height of the tunnel determines the length of the tunnel due to the fact that if the hanging curtain is too close to the scanner beam when the curtain is pushed back by the object being conveyed, it would obscure the X-ray scan beam or other source of radiation or linear or confined matter needing to be contained for safety, and therefore block or distort the imaging or processing.
Therefore, the length of the tunnel in the prior art must be at least twice the height of the tunnel. These long lengths result in long, bulky machines that are difficult to transport, including through elevators, store and to locate at sites where space is at a premium. The prior art machines are heavier, use substantially more structural and other material and safety shielding material, generally more attachment points and welds, and are more expensive. For the above reasons, prior art scanner apparatus are more difficult to see around (or easier to hide behind due to larger size). Cost of space per square meter is constantly rising, and tunnel scanning apparatus are popular in cities and high rise government buildings.